Extensive Pollen Flow and Historical Population Expansions Shaped the Phylogeographic Pattern of Choerospondias axillaris : Evidence From Chloroplast DNA and ITS Sequences

ABSTRACT Choerospondias axillaris is an ecologically and economically important tree species, yet its phylogeographic pattern remains insufficiently understood. We analysed 29 natural populations of C. axillaris in China based on three chloroplast DNA (cpDNA) and internal transcribed spacer (ITS) sequences. The MaxEnt model was then employed to forecast changes in suitable habitats under four climate scenarios. The results show that C. axillaris exhibits moderate genetic diversity (cpDNA: H t = 0.585; ITS: H t = 0.301). CpDNA genetic variation mainly exists among populations (61.51%), whereas ITS genetic variation is primarily concentrated within populations (90.17%). This pattern indicates that seed dispersal is limited, but pollen‐mediated gene flow is extensive. Neutrality tests and mismatch distribution analyses suggest that C. axillaris has undergone significant and recent population expansion in its history. We infer that the Xuefeng Mountains‐Wushan region in central China may have served as a significant glacial refuge. After the Last Glacial Maximum, C. axillaris expanded southwards (such as Guangdong) from this region to establish the current distribution patterns. Future climate warming may drive its suitable habitats northwards to areas south of the Qinling Mountains. Therefore, priority should be given to protecting identified genetic diversity hotspots and potential refuge populations while implementing targeted management for populations with low genetic variation to ensure the species' evolutionary potential.